Device and method for wound therapy

ABSTRACT

A wound therapy device is disclosed. The wound therapy device may include a housing for covering at least a portion of a wound and for sealing to a body surface of a patient. The housing may also include a liquid collector for retaining liquid therein and a vacuum connection for coupling to a vacuum source. The vacuum connection may be in gaseous communication with the liquid collector. The vacuum connection may be separated from the liquid collector by a liquid barrier.

RELATED APPLICATIONS

This application is a continuation application of pending U.S. patentapplication Ser. No. 12/592,049, filed Nov. 18, 2009, which is adivisional application of U.S. patent application Ser. No. 11/610,458,filed Dec. 13, 2006 (now U.S. Pat. No. 7,779,625), which is acontinuation-in-part of, and claims priority to, U.S. patent applicationSer. No. 11/432,855, filed on May 11, 2006 (now U.S. Pat. No.7,615,036), all of which are incorporated herein by reference.

TECHNICAL FIELD

The disclosure relates in general to a device and method for woundtherapy that is capable of treating a variety of chronic and acute woundtypes, including, but not limited to, infection wounds, venous ulcers,arterial ulcers, diabetic ulcers, burn wounds, post amputation wounds,surgical wounds, and the like. Specifically, the present disclosure isrelated to wound treatment devices and methods that utilize negativepressure therapy.

BACKGROUND

Negative pressure therapy has been one tool used for the treatment of avariety of wounds by practitioners in the art. Conventional devices aregenerally large in size and often require the use of complicatedequipment such as suction pumps, vacuum pumps and complex electroniccontrollers. Other associated equipment may include wound liquid/exudatecollection canisters, liquid transporting conduits, and pressureregulators/transducers/sensors. As a result, such devices may be bulky,power intensive, relatively costly and substantially non-disposable.Furthermore, the complexity of conventional devices requires steadypatient supervision and that initial placement and any changing of thedevices be conducted by a physician or nurse. At present, a typical costfor the use of these devices is on the order of about $100 per day perpatient.

The rising costs of healthcare and of medical devices place pressure onpatients and care providers alike to seek out solutions that allow useby a patient in-home, with less supervision. Furthermore, patientscontinue to demand devices that are more easily portable to allow traveland mobility.

BRIEF SUMMARY

The present disclosure provides a self-integrated wound therapy devicefor providing negative pressure therapy to a wound. In one embodiment,the device may include a housing to cover at least a portion of a wound.The device may also include a liquid collector within a liquid retentionchamber and an adaptor or coupling for coupling to a vacuum source. Thevacuum connection may be in gaseous communication with theliquid-retention chamber. The vacuum connection may be separated fromthe liquid collector by a liquid barrier. The wound therapy device mayalso include a seal to seal the housing to a body surface of a patient.

The vacuum connection in some embodiments may be coupled to a vacuumsource that may be optionally located within or adjacent to the housing.In other embodiments, the vacuum connection may comprise an adapter thatmay be coupled to a vacuum source located external to the housing. Asused throughout this specification, adapter and coupler or coupling maybe used interchangeably.

In other embodiments, the wound therapy device may be modular in nature,optionally including a wound interface module, a retention module and avacuum source module. Each module of the wound therapy device may beoptionally replaceable individually or in combination.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The present embodiments will become more fully apparent from thefollowing description and appended claims, taken in conjunction with theaccompanying drawings. Understanding that the accompanying drawingsdepict only typical embodiments, and are, therefore, not to beconsidered to be limiting of the scope of the present disclosure, theembodiments will be described and explained with specificity and detailin reference to the accompanying drawings as provided below.

FIG. 1 is a perspective view of one embodiment of a wound healingdevice.

FIG. 2 is a side cross-sectional view of the wound healing device ofFIG. 1.

FIG. 3 is a side cross-sectional view of another embodiment of a woundhealing device including a droplet gap as a liquid barrier.

FIG. 4 is a magnified view of the droplet gap of the device of FIG. 3.

FIG. 5 is a top cross-sectional view of the droplet gap of the device ofFIG. 3.

FIG. 6 is a side cross-sectional view of another embodiment of a woundhealing device including an internal vacuum pump as the vacuum source.

FIG. 7 is a side cross-sectional view of another alternative woundhealing device including an internal vacuum pump as the vacuum source.

FIG. 8 is side cross-sectional view of another embodiment of a woundhealing device with a housing of elongate shape.

FIGS. 9A and 9B are schematic views of wound healing devicesillustrating a modular approach to the device construction.

FIG. 10 is a perspective view of structural and absorbent material thatmay be disposed within a liquid-retention chamber of a wound healingdevice.

FIG. 11 is a side cross-sectional view of another embodiment of a woundhealing device.

FIG. 12 is a side cross-sectional view of another embodiment of a woundhealing device.

FIG. 13 is a side cross-sectional view of another embodiment of a woundhealing device.

FIG. 14 is a side cross-sectional view of another embodiment of a woundhealing device.

FIG. 15 is a side cross-sectional view of another embodiment of a woundhealing.

DETAILED DESCRIPTION

It will be readily understood that the components of the embodiments asgenerally described and illustrated in the Figures herein could bearranged and designed in a wide variety of different configurations.Thus, the following more detailed description of various embodiments, asrepresented in the Figures, is not intended to limit the scope of thepresent disclosure, but is merely representative of various embodiments.While the various aspects of the embodiments are presented in drawings,the drawings are not necessarily drawn to scale unless specificallyindicated.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

Reference throughout this specification to features, advantages, orsimilar language does not imply that all of the features and advantagesthat may be realized with the present invention should be or are in anysingle embodiment of the invention. Rather, language referring to thefeatures and advantages is understood to mean that a specific feature,advantage, or characteristic described in connection with an embodimentis included in at least one embodiment of the present invention. Thus,discussion of the features and advantages, and similar language,throughout this specification may, but do not necessarily, refer to thesame embodiment.

Furthermore, the described features, advantages, and characteristics ofthe invention may be combined in any suitable manner in one or moreembodiments. One skilled in the relevant art will recognize that theinvention can be practiced without one or more of the specific featuresor advantages of a particular embodiment. In other instances, additionalfeatures and advantages may be recognized in certain embodiments thatmay not be present in all embodiments of the invention.

Reference throughout this specification to “one embodiment,” “anembodiment,” or similar language means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the present invention. Thus,appearances of the phrases “in one embodiment,” “in an embodiment,” andsimilar language throughout this specification may, but do notnecessarily, all refer to the same embodiment.

In the following description, numerous specific details are provided,such as examples of housings, barriers, chambers etc., to provide athorough understanding of embodiments of the invention. One skilled inthe relevant art will recognize, however, that the invention can bepracticed without one or more of the specific details, or with othermethods, components, materials, and so forth. In other instances,well-known structures, materials, or operations such as vacuum sourcesare not shown or described in detail to avoid obscuring aspects of theinvention.

Referring now to FIGS. 1 and 2, a wound therapy device 10 is shown. FIG.1 shows a wound therapy device shown in a perspective view as would beattached to a body surface of a patient for at least partiallyencompassing a wound. FIG. 2 shows a side cross-sectional view of thedevice of FIG. 1 taken along plane 2-2 of FIG. 1. The device 10 includesa housing 20 configured to cover at least a portion of a wound. Thehousing 20 defines an internal space 22. In one embodiment, the internalspace 22 may contain a vacuum chamber 24 and a liquid-retention chamber40 separated by a liquid barrier 36. The liquid-retention chamber 40 mayinclude a liquid collector (not shown) for collecting wound exudate orother liquid. The housing is configured to be in fluid communicationwith a vacuum source (not shown). The liquid collector retains woundexudate while simultaneously communicating negative pressure generatedby the vacuum source to the wound. As used throughout thisspecification, negative pressure and vacuum may be used interchangeably.

In one embodiment the housing 20 is rigid or semi-rigid. The housing 20of the device 10 substantially retains its size and structure during theapplication of negative pressure, thus allowing a vacuum to be heldwithin the housing 20. The housing 20 may be produced out of anysuitable material known to one of ordinary skill in the art, including,without limitation, rubbers, including polyurethane, and dense plasticssuch as, but not limited to, polypropylene, polyvinyl chlorides,polyethylene, acrylonitrile-based copolymer, such as those sold underthe Barex® brand, polyester, polystyrene, polyether, nylon,polychlorotrifluoroethylene, fluoropolymer, polytetrafluoroethylene,such as those sold under the Teflon® brand, silicone, neoprene orcombinations thereof and similar materials.

In another embodiment, the housing 20 is made of a flexible barrier or asurface wrap supported by at least one customizable rigid or semi-rigidstructural support (not shown) present within the internal space 22 ofthe housing to maintain the shape of the device when the device issubjected to pressure lower than atmospheric pressure. In someembodiments, the structural supports may be external to the housing orintegral with the housing 20. The flexible barrier or surface wrap maybe a thin polyurethane film with a dermal compatible adhesive supportedby structural foam present within the internal space 22 of the housing20. The structural supports or structural foam can be made from rigid orsemi-rigid plastics and foams, e.g., polystyrene, polyester, polyether,polyethylene, silicone, neoprene, combinations thereof, and the like.Alternatively, the liquid-retention chamber 40 or a liquid collectorpositioned therein may by itself provide the needed structural supportto maintain vacuum passages within the housing 20 open upon applicationof vacuum.

In one embodiment, the housing 20 is semi-permeable. An exemplarysemi-permeable housing 20 may be substantially impermeable to liquidsbut somewhat permeable to water vapor and other gases while capable ofmaintaining a negative pressure underneath the housing 20 uponapplication of a vacuum. By way of example, the housing 20 material maybe constructed of polyurethane or other semi-permeable material such asthose sold under the Tegaderm® brand. In one embodiment the housing 20may have a water vapor transmission rate (“WVTR”) of about 836grams/m²/day or more. However, in other embodiments the WVTR may be lessthan about 836 grams/m²/day. In yet other embodiments, the housing 20material may be substantially impermeable to both liquids and gases(including water vapor). Other exemplary housing materials may includematerials sold under the Opsite®, Suresite®, Medfix®, and Mefilm® brandnames.

The device may be made of material to make it conformable for use withwounds in various locations. For example, the wound may be on an elbowor other joint such the device may need to be conformed to make a goodseal around the wound site.

The vacuum source (not shown) is in fluid communication with the housing20. A vacuum connection 30 may connect the housing 20 and the vacuumsource. The vacuum connection may include without limitation, flexibleor semi-rigid medical tubing known in the art, a plenum, a conduit, orother passage capable of transmitting the vacuum from the vacuum sourceto the housing 20. In one embodiment, the housing is fitted with anadaptor 32 or coupling 32 that allows the housing 20 to be attached tothe vacuum connection 30 or to an external vacuum source. The vacuumsource may be located internal to or external to the housing 20 and maybe remote or adjacent to the housing. Where the vacuum source isexternal to the housing 20 and adjacent the housing 20, the vacuumconnection 30 may not be necessary and the vacuum may be communicated tothe housing 20 directly from the vacuum source through the adapter 32 orcoupling 32. In embodiments, wherein the vacuum source is within thehousing 20, the adapter 32 or coupling 32 may not be needed. The vacuumsource may be a micro-vacuum pump or a regular vacuum pump. The pumpsmay be of any kind known to those skilled in the art. The vacuum sourcemay also be an osmotic or electroosmotic pump.

The vacuum source may include and operably be coupled to a power sourceor supply, such as a battery. Power sources referred to herein may be,for example, electrical outlets, batteries, and/or rechargeablebatteries and the like. The batteries may be integral (non-replaceable),replaceable and/or rechargeable. The power source may be locatedadjacent to the vacuum source or may be positioned remotely so that alarger capacity power source that could last for the duration of thetreatment can be used.

The adapter 32 or coupling 32 can simply be a vacuum port for connectingan outlet of the vacuum source. The adapter 32 or coupling 32 can alsobe configured to provide more complex communication between the housing20 and the vacuum source. The adapter 32 or coupling 32 may be fitted tocarry communication channels and/or lines between a control module inthe vacuum source or vacuum source module and sensors positioned withinthe interior of the housing 20.

In one embodiment, the adapter 32 or coupling 30 is in gaseouscommunication with the vacuum chamber 24, which in turn is incommunication with the liquid-retention chamber 40 via the liquidbarrier 36. In an alternative embodiment, the vacuum connection 30 isdirectly in communication with the liquid-retention chamber 40 via theliquid barrier 36. In another alternative embodiment, the outlet of thevacuum source is directly connected to the liquid barrier. The vacuumsource, the vacuum 30 connection and the vacuum chamber 24 and theliquid barrier 36 may all be external or internal to the housing.

The adapter 32 or coupling 32 may be a design feature associated withthe housing 20 or vacuum source to allow the housing 20 and vacuumsource to be coupled together. This coupling may be accomplished byinterference fit, snap fit, compression fit, and the like. The adapter32 or coupling 32 may also be accomplished by adhesion or a bymechanical device as is known in the art to provide a coupling formaintaining the vacuum source in communication with the housing. Theadapter 32 or coupling 32 is configured to transfer negative pressuregenerated by the vacuum source to the housing 20.

The vacuum chamber 24 of the embodiment of device 10 illustrated in FIG.1 is defined by the interior of the housing 20. The vacuum chamber 24may be an empty space or may be filled with a porous material thatallows communication of the vacuum. The vacuum chamber 24 establishes apositive connection for the vacuum force or pressure that enhances thedistribution or transfer of the vacuum pressure to the liquid collector.The vacuum chamber 24 may also serve to distribute the vacuum pressuremore evenly to the liquid collector. It will be appreciated by those ofskill in the art that the vacuum chamber need not be defined by thehousing 20, but may also be outside the housing. For example, the vacuumchamber 40 may be the conduit in the vacuum connection 30. The vacuumchamber 40 may also be within space defined by the adapter 32.

The liquid collector includes at least one porous material that includesa plurality of passages to allow fluid communication between the vacuumsource and the wound through the liquid collector. The liquid collectormay include structures and/or substances to assist in retaining theliquids drawn from the wound. Such structures and/or substances mayinclude sponges, foams, fibers, wicking fibers, hollow fibers, beads,fabrics, or gauzes, super-absorbent materials including super-absorbentpolymers in various forms, absorbent foams, gelling agents such assodium carboxy methyl cellulose, packing materials, and combinationsthereof. Such structures or substances have passages that permit theflow of gas and allow the vacuum or negative pressure to be applied tothe wound. These structures or substances also absorb and retain liquiddrawn out of the wound. It will be appreciated by those of skill in theart that liquid in the form of wound exudate may include solidcomponents such as cellular debris and other solids that are typicallyfound in wound exudates.

The materials or structures that make up the liquid collector form orcontain interstitial spaces that serve as negative pressure passageways.These allow the vacuum source to be in fluid communication with thewound through the liquid collector. In one embodiment, the liquidcollector may be a composite structure of fibers made of polyester orrayon with superabsorber fibers made of sodium polyacrylate among othersdispersed throughout the structure to form a fiber matrix. Thesuperabsorber fibers or particles are distributed discretely within thefiber matrix such that the gas (vacuum) passage ways are open even aftersubstantial liquid uptake by the superabsorber fibers or particles. Thesuperabsorber fibers may act as, or contain, nodes within the liquidcollector. As liquid is absorbed by the liquid collector, the liquidcollects at the super absorber nodes without blocking the gas (vacuum)passageways within the liquid collector. In another embodiment, thewound exudates that enter the liquid collector are absorbed by thesuperabsorber material and are immobilized at discrete locations withinthe fiber matrix or other liquid collector material. Thus, the liquidcollector retains the liquid during the application of vacuum as well aswhen the vacuum is off.

In another embodiment, the liquid collector has areas or zones that areprevented from becoming saturated or super saturated. In theseembodiments, the non saturated zones or areas make up the passages forcommunication vacuum or negative pressure from the vacuum source throughthe liquid collector to the wound. Accordingly, the device 10 includesmeans for maintaining a therapeutic pressure at the wound while theliquid collector is absorbing liquid.

In one embodiment, the liquid collector, housing 30, and/or liquidretention chamber 40 is sufficiently rigid to allow fluid communicationbetween the vacuum source and the wound through the liquid collectorwhen the device is subject to a pressure lower than atmosphericpressure. The device 10 has sufficient rigidity or structure so that thepassages through the liquid collector will remain open under vacuumpressure, thus allowing vacuum or negative pressure to be transmitted tothe wound.

The liquid collector is configured to retain liquid under apredetermined amount of mechanical force applied to the liquidcollector. For example, the liquid collector may retain liquid even whenthe device 10 is squeezed by a user. This feature prevents oozing offree liquid from the liquid collector when the vacuum source is off orwhen the retention chamber or liquid collector needs to be replaced.

In one embodiment, the liquid collector is a composite structure made ofa structural fiber matrix with superabsorber fibers dispersed within.Such a structure maintains sufficient structural integrity under theapplication of vacuum to keep vacuum passages open. Hence no additionalstructural supports are needed.

Other means for collecting and retaining liquid having similar featuresthat are known to one of ordinary skill in the art may also be used. Insome embodiments, the liquid collector or the liquid-retention chamber40 may be antimicrobial in nature or may include antimicrobial agents.

The liquid collector may be within the liquid-retention chamber 40, ormay be part of the structure that defines the liquid-retention chamber40. As used herein, “retaining liquid” or “the retention of liquid”means substantially retaining the liquid. In some embodiments, theliquid-retention chamber itself can provide the needed structuralsupport to maintain vacuum passages within or through the housing openupon application of vacuum. Thus, the device has sufficient structure tomaintain the functionality of the device under application of a vacuum.As will be discussed in greater detail below, a fill indicator may alertthe user at a predetermined liquid collector saturation point.

The liquid barrier 36, in one embodiment, is positioned between thevacuum source and the liquid collector (not shown). The liquid barrier36 serves to prevent travel of liquid from the liquid-retention chamber40 to the vacuum chamber 24. The liquid barrier 36 may also be a gaspermeable membrane. As such, it may comprise any of a large family ofsuitable technologies that prevent travel of liquid from theliquid-retention chamber 40 into the vacuum chamber 24 while allowinggas flow, and thus transmission of negative pressure provided throughthe vacuum connection 30. It will be appreciated by those of skill inthe art that the liquid barrier 36 may be in the form of a film, a mat,a membrane or other structure that is liquid impermeable. For example,the liquid barrier 36 may include a porous hydrophobic film, a poroushydrophobic membrane, or other hydrophobic structure, or other ways topreclude moisture travel.

Examples of porous hydrophobic films include, but are not limited to,porous and microporous polytetrafluoroethylene, polypropylene,polyvinylidene difluoride, acrylic polymers, polyethylene, or fibrouslayers of each and combinations thereof. For example, porous hydrophobicfilms sold under the Gore-Tex® or Millipore® brands may be suitable.These hydrophobic films may also act as anti-microbial filters andprevent passage of bacteria from the liquid-retention chamber to thevacuum source and vice versa. Other technologies that allow gas flow butprevent liquid flow may also be used as suitable liquid barriers 36 aswould be apparent to those having skill in the art with the aid of thepresent disclosure.

In the device 10 of FIG. 2, the liquid barrier 36 is a poroushydrophobic film configured to allow gas flow while at leastsubstantially blocking liquid flow. Thus, when a vacuum source (notshown) is attached to the means of communicating the vacuum, which inthe illustrated embodiment is the adapter 32 of the vacuum connection30, negative pressure is supplied/transmitted through the vacuum chamber24 into the retention chamber 40, drawing liquid from the wound siteinto the liquid-retention chamber 40.

In one embodiment, the wound therapy device 10 includes means formaintaining operation of the device independent of device orientation.For example the device may need to be located at various locations onthe patient's body and must function at different angles including whenthe device is completely inverted. In one embodiment, the means formaintaining the functionality of the device independent of deviceorientation includes the liquid barrier 36 which keeps moisture out ofthe vacuum source regardless of device orientation. The means alsoincludes the individual components of the device which are designed tobe orientation independent. The means for maintaining the deviceoperation independent of the device orientation may include the liquidcollector being fabricated from a material which gels and immobilizesthe wound exudates thereby preventing clogging of vacuum passageways bythe free liquid. For example, where the liquid collector includes afibrous matrix with supper absorber nodes dispersed throughout thematrix, the exudate may gel at the nodes removing the liquid whilecontinually providing vacuum passageways.

The device 10 may additionally contain a wound interface 41 in directcontact with the wound and may comprise single or multiple layers ofvarying thicknesses to accommodate the depth of the wound. The woundinterface 41 may be either placed directly inside the wound or over thewound. The wound interface 41 is in fluid communication with theliquid-retention chamber and is configured to transfer wound fluid froma wound bed to the liquid-retention chamber 40. In one embodiment, thewound interface 41 transfers fluid by wicking action. In anotherembodiment, the wound interface 41 transfers fluid by capillary action.The wound interface 41 may be porous to allow wound fluid to passthrough for absorption by the overlying liquid collector. Alternatively,the wound interface 41 may partially or fully absorb wound fluids. Thewound interface 41 may be a sheet, a foam, a gel, a gauze, a porousmatrix, a honeycomb, a mop, confetti, and combinations thereof.

The wound interface 41 may be either placed directly inside the wound orover the wound. The wound interface 41 may serve many functions such asbeing a layer that allows supply of vacuum to the wound while allowingeasy and painless removal from the wound site of the liquid-retentionchamber 40 after it reaches a predetermined absorption level. The woundinterface 41 may be degradable copolymer foil, such as those sold underthe Topkin® brand, or a layer that provides beneficial bioagents in theform of specialized dressings such as dermal regeneration templates(e.g., those sold under the Integra® brand), bioabsorbable gels, foamsand barriers that prevent tissue adhesion (e.g., those sold under theIncert® brand), a skin substitute (e.g., those sold under the BioFill®brand), a layer for selectively maintaining moisture at the wound site(e.g., alginates or dressings such as those sold under the Alevyn®brand), a layer that is angiogenic (e.g., those sold under the Theramersbrand), and/or a layer that is antimicrobial or includes anantimicrobial agent.

The wound interface 41 may take a variety of forms including but notlimited to a sheet, foam, gel, gauze or other space filling porousstructures such as a pouch of beads, a shaggy mop, loose confetti or ahoney comb. Alternatively, the wound interface 41 can be a gel thatfills the wound cavity, which turns into a porous structure onapplication of the vacuum. In one embodiment, the wound therapy deviceincludes a surface in contact with the wound having at least one porelarger than about 100 microns in diameter.

It will be appreciated by those of skill in the art that the woundinterface 41 and liquid collector may be combined in a variety of waysto accomplish the teachings of the invention. For example, the woundinterface 41 and liquid collector may be separate layers of an integralbody. In one embodiment, a plurality of the liquid collectors may eachbe enclosed within a pouch that acts as the wound interface. The coverof the pouch is fabricated from the wound interface formed from a porousmaterial that is permeable to vacuum and body fluids. Liquid collectormaterial is enclosed within this porous pouch. In one embodiment thewound interface prevents direct contact between the liquid collectormaterial and the wound. However, it is contemplated that in someembodiments there may be some contact. This wound interface/liquidretention combination can take many forms including pillows, tubes,self-contained tubular structures and similar structures where theliquid collector can be enveloped in the wound interface. Thesestructures are flexible and can be formed into a suitable shape to fitany kind of wound cavity. Alternatively, several of these pouches can belinked together or otherwise combined to form structures that can beinserted into a deep wound tunnel or deep wound cavity. For example, alinked tubular chain can be formed that can be inserted within a woundtunnel such that the entire wound cavity is filled with this chainedstructure. A flexible barrier housing material such as Tegaderm can thenbe used to cover the wound site and seal on the skin around the woundsite. The module containing the vacuum source is attached to theflexible barrier housing to create vacuum within the wound cavity. Woundexudate enters the inside of the pouch through the permeable outer woundinterface cover and gets absorbed within the liquid collector. Asbefore, the liquid collector will permit application of vacuum to thewound while absorbing and retaining liquid drawn out of the wound.

As will be discussed in greater detail below, the device 10 may includea skin protection layer. The skin protection layer may protect thehealthy skin around the wound from bruising or maceration due toundesirable exposure of the healthy skin to vacuum and moisture duringwound therapy. Such a skin protection layer will allow the healthy skinto “breathe” and also allows easy and painless removal of the devicefrom the wound site. The skin protection layer may be sealed separatelyto the skin first and the housing may be then sealed to the skinprotection layer. Alternatively, the skin protection layer may beintegral to the housing or the wound interface. The skin protectionlayer may be the same as the housing material or may be a gel.

When the device 10 is placed on a patient and activated, or attached toan external vacuum source via a vacuum connection 30 or simply throughan adapter 32, the device 10 delivers negative pressure to the wound.The device 10 is generally attached to the body surface of a patientusing one of a variety of seals known in the art, such as, in oneembodiment, a housing seal 28. The housing 20 of the device 10 may beadapted to be sealed to a body surface of a patient. In someembodiments, this sealing may occur simply as a result of placing thehousing 20 against the body surface and drawing a vacuum within thedevice 10. The device 10 may include a seal 28 for attaching the deviceto a surface. Adhesives, gaskets, and other seals or sealingtechnologies known to one of ordinary skill in the art may also be usedas a seal 28 including the use of adhesive backed thin polyurethanefilms. Other suitable seals are known to those of ordinary skill in theart and may be used with the embodiments disclosed. In one embodiment,the device includes a leak detector in operable communication with theseal to determine whether vacuum or negative pressure is escaping fromthe device 10 out the seal 28.

In one embodiment, the seal 28 may be part of housing 20 or may beintegral with the skin protection layer. It will be appreciated by thoseof skill in the art that the seal 28, housing 20 and skin protectionlayer may be combined in a variety of different ways to accomplish theteachings of this invention.

Thus, in operation, the device 10 may be applied to a wound site of apatient like a patch, wherein a vacuum source coupled to the vacuumconnection 30, provides negative pressure to the wound. Prior to use,the device 10 may be packaged to prevent contamination. Such packagingcould be a bag or envelope, or could include the use of an optionalprotective cover 16, with an optional pull tab 18 that is removed fromthe device prior to placement on the patient. During application ofnegative pressure to the wound site, liquid is drawn into theliquid-retention chamber 40 and held within the liquid-retention chamber40, being prevented from further travel by the liquid barrier 36.

Referring now to FIG. 3, another embodiment of a wound therapy device110 is shown from a side cross-sectional view analogous to that of FIG.2. The wound therapy device 110 of FIG. 3 includes a housing 120 and avacuum passage 130. In the device 110 of FIG. 3, the vacuum passage 130is a port 132 adapted to receive an external vacuum source through avacuum connection 134 in a sealed manner, such that the vacuum sourcemay apply a negative pressure to the device 110. In alternativeembodiments, the vacuum source may be adjacent to and internal orexternal to the housing 120. In an exemplary device 110, the vacuumsource not shown may be shared between a series of devices 110 on asingle patient, or between several patients since no liquid passes intothe respective vacuum connections 134 by the respective devices 110. Aswith the device 10 of FIGS. 1 and 2, the wound therapy device 110 ofFIG. 3 may include a liquid-retention chamber 140 and a vacuum chamber124. In this embodiment, the vacuum chamber 124 itself serves as aliquid barrier 136, acting as a “droplet gap” unable to be traversed byliquids drawn into the liquid-retention chamber 140. The “droplet gap”refers to the gap between the liquid retention chamber 140 and thevacuum passage 130. The surface tension of the liquid present in theliquid retention chamber prevents droplets from jumping the “dropletgap” to the vacuum passage. Therefore the “droplet gap” acts as a liquidbarrier to prevent liquid from leaving the liquid retention chamber 140.

More specifically, the vacuum chamber 124 may be a cylindrically-shapedvoid within the internal space 122 of the housing 120, which, due to itssize, prevents liquid from traveling from the liquid-retention chamber140 into the vacuum passage 130. The vacuum passage 130 may extend intothe vacuum chamber 124, and may include at least one orifice 138. Thehousing 120 may also include internal supports 126 that extend betweenthe vacuum passage 130 and the perimeter 142 of the liquid-retentionchamber 140 to maintain proper distance between the vacuum passage 130and the liquid-retention chamber 140.

A labyrinth may also be used as a liquid barrier to prevent liquid fromleaving the liquid retention chamber 140. The labyrinth approachutilizes the principle of coalescence and employs structures used incommercially available mist eliminators as are well understood bychemical engineers. Liquid or mist that enters the labyrinth willcoalesce and will be redirected back to the liquid retention chamberwithout entering the vacuum passage 130.

The wound therapy device of FIGS. 1 and 2 could be modified to takeadvantage of the droplet gap principle illustrated in FIG. 3 simply byomitting the liquid barrier 36. The droplet gap or labyrinth means mayalso be effectively used instead of a hydrophobic liquid-barrier formaintaining a vacuum within the device independent of deviceorientation.

Referring again to FIG. 3, the device 110 may optionally include aliquid barrier 136 in the form of a porous hydrophobic membranepositioned between the liquid retention chamber 140 and the vacuumchamber 124.

FIG. 4 is a detail view of the vacuum chamber 124 and liquid barrier 136of the device 110 of FIG. 3 showing the contents of circle 4 of FIG. 3.As depicted, internal supports 126 structurally locate the vacuumpassage 130 within the vacuum chamber 124.

The exemplary structure, shape, and construction of the vacuum chamber124 of the device 110 is further illustrated in FIG. 5, which is across-sectional view of the wound therapy device 110 of FIGS. 3 and 4taken along plane 5-5 of FIG. 3. Internal supports 126 extend betweenthe vacuum passage 130 and the perimeter 142 to maintain proper distancebetween the vacuum passage 130 and the liquid-retention chamber 140. InFIG. 5, the vacuum chamber 124 is illustrated to have a cylindricalprofile. It should be noted that variation of the size, volume, or shapeof the vacuum chamber 124 is within the skill of one of ordinary skillin the art. Thus, elliptical, rectangular, and other shapes, withoutlimitation, are considered to be within the scope of the presentdisclosure.

The liquid barriers and/or vacuum chamber configurations described aboveinclude passages that form part of the passage between the vacuum sourceand the wound that carries the negative pressure to the wound.Accordingly, these configurations form part of the means forcommunicating a vacuum between the vacuum source and the wound.

Referring next to FIG. 6, another embodiment of the wound therapy device210 is shown in a side cross-sectional view analogous to that of FIG. 2.The device 210 of FIG. 6, like those previously illustrated, includes ahousing 220 that encloses an internal space. This embodiment of thewound therapy device 210, however, is configured to include a negativepressure source 230, including a vacuum source 234 and an adaptor 232that supplies negative pressure to the vacuum chamber 224. The vacuumsource 234 is operably coupled to a power source 238 which together maybe internal to the device 210 as illustrated. Further, although thevacuum source 234 and power source 238 are illustrated to be internal tothe housing 220, in an auxiliary chamber 226 in FIG. 6, it should beunderstood that such apparatus may be located outside of the housing220, or may alternatively be placed in a modular portion of the device210 which may be removed and replaced as needed.

In some embodiments, negative pressure may be applied to theliquid-retention chamber 240 and/or liquid collector via a tube or othercoupling 232 or adapter 232 attached to the vacuum pump 234. When thevacuum source 230 is an internally-placed vacuum pump 234, the coupling232 may travel from the pump 234 to the vacuum chamber 224 in gaseouscommunication with the liquid-retention chamber 240. When the vacuumsource 230 is an internally-placed vacuum pump 234, an outlet 235 isprovided for the vacuum pump or other vacuum source to vent. The outletmay include a filter 237 to prevent germs from outside from enteringinside or vice-versa. The opening of the coupling 232 in the vacuumchamber 224 may include a filter 261 or can have similar properties tothe liquid barrier 236 (such as, in some embodiments, as anantimicrobial filter) to prevent wound liquids from reaching the vacuumsource 230 and to prevent any outside germs from entering the woundsite. Moreover, in some embodiments the device 210 may include bothinlet and outlet filters to prevent venting of microorganisms outsidethe housing 220.

In operation, the wound therapy device 210 may first be placed on a bodysurface of a patient so as to at least partially enclose a wound area.As discussed above, the device 210 may be sealed to the body surfaceusing either just the suction generated by the device 210 alone, orusing a seal 228 chosen from those known to those skilled in the art.The seal 228 illustrated in FIG. 6 is an adhesive seal covered duringstorage by a cover 216, optionally including a pull tab 218. The device210 may further include a wound interface 241 as described herein.

Following attachment of the device 210 to a patient, the vacuum source234 is activated, reducing the internal pressure of the device 210. Asnegative pressure is generated, liquids are drawn from the wound intothe liquid-retention chamber 240 of the device 210, and are blocked fromfurther progress into the vacuum chamber 224 or the negative pressuresource 230 by the liquid barrier 236. As in the previous embodiments,the liquid barrier 236 may be any of those known to those of ordinaryskill in the art, including, without limitation, porous hydrophobicfilms, membranes, and porous hydrophobic structures such as spongesand/or foams.

The exemplary device 210 of FIG. 6 may further comprise a pressurerelief valve 260, a fill indicator 270, and a non-seal indicator (notshown). In some specific embodiments, the housing 220 may furtherinclude means for controlling pressure within the housing. The means forcontrolling pressure may include without limitation, a pressure reliefvalve or a pressure control valve or other pressure controller. Thepressure relief valve 260 may be used to maintain negative pressurewithin the internal space of the housing 220 (and thus within theliquid-retention chamber 240 and at the wound surface) at a therapeuticvalue. Pressure relief valves may be any of the kind commerciallyavailable. In one embodiment, the negative pressure is maintainedbetween about 75 mm Hg to about 125 mm Hg. The pressure relief valve canbe located anywhere on the device where the vacuum is established. Inone embodiment, the pressure relief valve 260 is located on the housing220 so that it can respond to changes in the liquid-retention chamber240. The pressure relief valve 260 may also be located on the vacuumsource itself or in between the housing and the vacuum source 230. Thepressure relief valve 260 may additionally include an inflow filter (notshown) to prevent entry of contaminants into the device 210, and thus tofurther protect the wound site. The pressure relief valve could operatein a variety of ways, including opening at a pre-set pressure point toallow ambient air to enter inside the housing 220 and closing after apre-set pressure value is reached inside the housing 220, opening thedevice 210 and deactivating the vacuum source, or simply deactivatingthe vacuum source. It will be appreciated by those of skill in the artthat the controlling the pressure within or without the device 10includes turning on or off the vacuum source.

The wound healing device 210 may alternatively include a pressurecontroller for controlling the vacuum or pressure with in the housing220. The pressure controller may work in cooperation with a vacuum(pressure) sensor to detect the pressure within the wound cavity and/orover the wound within the liquid-retention chamber 240. The vacuumsensor is connected to the vacuum source 234 via a circuit board/relaycombination and controls the vacuum source. The vacuum sensor mayalternatively be coupled to the pressure relief (control) valve 260 tomaintain therapeutic vacuum at the wound site. Vacuum (pressure) sensorsor differential pressure sensors may provide a voltage output or acurrent output which signal can be used by a circuit board/relaycombination to turn on or turn off the vacuum source. Examples of suchelectronic vacuum sensors are those commercially available fromHoneywell under the trade name Sensotec sensors.

Alternatively, a vacuum switch or a differential pressure switch may beplaced that shuts off the vacuum source 30 when the desired pressure isreached without any pressure relief valve. Such mechanical vacuum(pressure) switches are well known for practitioners of the art and canbe purchased from MPL (Micro Pneumatic Logic), Air Troll, Air Logicamong others.

In still other embodiments, the device 210 may include a fill indicatorthat indicates when the liquid-retention chamber 240 has a predeterminedabsorption level. The fill indicator 270 may operate in a variety ofways known to one of ordinary skill in the art. Such indicators includethose that are visible (e.g., color change or LED) or audible. The fillindicator 270 may be advantageously placed on the external wall of thehousing 220 or near the vacuum source 234. The fill indicator 270 mayinclude a sensor component positioned inside the housing thatcommunicates electronically or mechanically with the fill indicator.Such a sensor may be placed either between the liquid-retention chamber240 and the liquid barrier 236 or on the wall of the liquid-retentionchamber opposite to the wound interface 241. Some sensors operate bydetecting presence of free moisture in the liquid-retention chamber 240,which denotes that the liquid-retention chamber has reached apredetermined absorption level. Alternatively, the fill indicator sensormay use electrical conductivity through a path in a portion of theliquid-retention chamber 240 to sense when moisture has reached the zoneand provide a signal to shut off the vacuum source 230. Other sensorsare known in the art and are suitable for use with the devicesdisclosed, including color-change technology based upon moisture contentof the material or a change in a physical feature or characteristic,vacuum sensors based on detection of vacuum changes, galvanic,potentiometric, and capacitive types. The device 210 may additionallyinclude an overflow valve such as a float valve for the vacuumconnection to prevent transmission of liquid into the vacuum source.

The wound healing device 210 may also alternatively include a lack ofvacuum or housing non-seal indicator or leak indicator (not shown). Suchan indicator may be based on pump run-time, low vacuum signal from thevacuum sensor, visible indicators on the housing (e.g., a dimple on thehousing that flattens or an embossed pattern on the housing that appearswhen the vacuum inside is at the appropriate level), low flow ratesensors, pressure sensitive color change, etc. The leak indicator may bein operable communication with the seal. The wound healing device 210may also optionally include a sensor to detect oxygen levels or othergasses and a sensor to measure temperature at the wound site. The device210 may also include a blood detector. In one embodiment, the blooddetector may use optical technologies known in the art to detect thepresence of blood within the housing 220.

In embodiments with sensors, other indicators, valves, switches, and thelike, the adapter may be configured with channels, ports, inlets oroutlets. For example, the adapter 232 may include communication leadsfrom a vacuum sensor, fill indicator sensor, seal sensor or othersensors or indicators present in the interior of the housing 220.Further, any communications between a pressure relief valve or over-flowvalve present on the housing 20 and the vacuum source can be channeledthrough such an adapter. In some embodiments, the adapter can alsofunction as an on-off switch where the vacuum source as well as all theother components in the device will start functioning when the vacuumsource is coupled to the housing 20 through the adapter.

FIG. 7 illustrates yet another embodiment of a wound therapy device 410.Wound therapy device 410 offsets the vacuum source 434 and itsassociated power source 438 further from the wound site, which togethermay or may not be within the housing. In some situations, the offset maybe beneficial for the wound. Similar to previous embodiments, the device410 may include a housing 420 that encloses an internal space 422. Thisspace 422 is subdivided into a vacuum chamber 424, a liquid-retentionchamber 440, and an auxiliary chamber 426. As with previously-discussedembodiments, however, it is optional to include the auxiliary chamber426, or to enclose the vacuum source 434 and power source 438 therein.When the vacuum source is an internally-placed vacuum pump 434, anoutlet 435 is provided for the vacuum pump to vent. The outlet mayinclude a filter 437 to prevent germs from outside from entering insideor vice-versa.

In this embodiment, the negative pressure source 430 extends through thehousing 420 into the vacuum chamber 424 at an outlet 432. The outlet 432may include a filter 461 (such as, in some embodiments, an antimicrobialfilter) to prevent entry of wound exudate into the vacuum source 434. Aswith the other embodiments, this device 410 may include a liquid barrier436, such as a hydrophobic membrane, that prevents flow of liquid intothe vacuum chamber 424, but allows the negative pressure to extend intothe liquid-retention chamber 440, causing liquid to be drawn into theliquid-retention chamber 440 from the wound. In some embodiments, thevacuum chamber 424 may include a porous hydrophobic foam. In otherembodiments, the vacuum chamber 424 may be empty.

As described herein, the device 410 may be sealed to the body surface ofa patient using either just the suction generated by the device 410alone, or using a seal 428 chosen from those known to individualsskilled in the art. The seal 428 illustrated in FIG. 7 is an adhesiveseal covered during storage by a cover 416, optionally including a pulltab 418. The device 410 may further include a wound interface 441 assimilarly described herein.

FIG. 8 illustrates an alternative embodiment of a wound therapy device510 that is applicable to assist in the healing of wounds located onparts of the body while standing, sitting, or laying, i.e., heel of thefoot or buttock. In those instances it may be desirable that the woundsite dressing and device components in the loaded areas substantiallyconform to the surrounding body so as to avoid pressure loading at thedevice site which may be detrimental to healing or could causeadditional wounds. Furthermore, it may be desirable to collect woundliquid or exudate at a position remote from, but still adjacent thewound site.

To accomplish this, the device 510 shown in FIG. 8 has an elongatedhousing 520 structure with a proximal end 527 configured to cover atleast a portion of the wound and a distal end 529 configured to beoutside the wound perimeter. The wound interface 541 is located at theproximal end 527. In one embodiment, the vacuum source 530 is attachedto the housing 520 adjacent the distal end 529. In another embodiment,the vacuum source 530 is attached to the housing 520 adjacent theproximal end 527. The liquid-retention chamber 540 extends from thewound interface 541 to the negative pressure source 530. In thisembodiment a majority portion of the liquid-retention chamber 540 is atthe end of the housing 520 adjacent the negative pressure source 530.The device 510 may also contain a liquid barrier 536 positioned betweenthe liquid-retention chamber 540 and the vacuum or negative pressuresource 530. In one embodiment, the liquid-retention chamber 540 extendsfrom within a wound perimeter to a position outside the wound perimeter.In another embodiment, the housing 520 includes a proximal end 527configured to cover at least a portion of the wound, and a distal end529 configured to be outside a wound perimeter.

The wound interface 541 located at the wound site seals the wound andallows application of negative pressure to the wound site. The woundinterface 541 may be in contact with the liquid-retention chamber 540which extends to the location of the vacuum supply chamber 524. Thisextended liquid-retention chamber 540 allows the placement of thenegative pressure source at a different location compared to a woundsite.

Alternatively, the device 510 may have two separate housings: onehousing 520 a having a sealing surface 512 around the wound site and theother housing 520 b being located at some distance away from the woundsite. The latter housing 520 b may or may not seal to the skin. Bothhousings 520 a, 520 b shown in FIG. 8 may be constructed of a liquidimpermeable flexible barrier optionally supported by rigid or semi-rigidsupport structures 526. The housing 520 b containing the vacuum chamber524 may be located more conveniently where loading due to sitting,standing, or lying will not occur or can be substantially avoided. Witha low aspect ratio, the device may be substantially planar over thewound site. In this configuration, pressure applied to the device willbe distributed over a greater area and not be directed into the wound.

The negative pressure source 530 may include a micro-vacuum pump 534operably coupled to a power source 538, such as a battery. The negativepressure source 530 may be external to the housing 520, as illustrated.However, it should be understood that alternative embodiments of thewound therapy device 510 may include the pump 534 which maybe amicro-vacuum pump and/or power source 538 internal to the housing 520.The negative pressure source 530 may be an osmotic or electroosmoticpump adjacent or internal to or adjacent the housing as discussed above.

FIGS. 9A and 9B illustrate embodiments of a wound therapy device 610,610′ that are modular in nature. In this embodiment, the device 610,610′ may separate into three modules. However, greater or less thanthree modules may be used as would be apparent to one having skill inthe art with the aid of the present disclosure. In the embodimentsdepicted, the device 610, 610′ includes a wound interface module 641,641′, a liquid-retention module 640, 640′, and a vacuum pump module 630,630′. Due to its modular nature, any one of the modules or combinationof modules of the device 610, 610′ can be replaced as needed.

For example, if the liquid-retention module 640, 640′ is filled to apredetermined level with exudate, it may be replaced with a newliquid-retention module 640, 640′, while keeping the functional vacuumpump module 630, 630′. Alternatively, the liquid-retention module 640,640′ may be replaced at regular intervals to prevent overflow and assureappropriate capacity. Likewise, the wound interface module 641, 641′ maybe replaced independent of the other modules.

In the embodiment of FIG. 9A, the liquid-retention module 640 is similarin design to the embodiments depicted in FIGS. 2 and 6. Theliquid-retention module 640′ of FIG. 9B is similar in design to theembodiment depicted in FIGS. 3 and 4. Both embodiments of device 610,610′ include a liquid barrier 636, 636′ to restrict exudate fromentering into vacuum chamber 624, 624′. The vacuum pump module 630, 630′may include a vacuum source 634, 634′, and optionally, a power source638, 638′. When the vacuum source 634, 634′ is internally placed, anoutlet 635, 635′ is provided for the vacuum source 634, 634′ to vent.The outlet 635, 635′ may include a filter 637, 637′ to prevent germsfrom outside from entering inside or vice-versa.

The wound interface module 641, 641′ of both embodiments may serve manyfunctions as described above, such as being a layer or other structurethat allows supply of vacuum to the wound while allowing easy andpainless removal from the wound site during dressing changes.Alternatively, the wound interface may be a layer or other structurethat provides beneficial bioagents in the form of specialized dressingssuch as dermal regeneration templates, bioabsorbable gels, foams andbarriers that prevent tissue adhesion. The wound interface may also be askin substitute, a layer for selectively maintaining moisture at thewound site, a layer that is angiogenic, and a layer that isantimicrobial. The wound interface may take a variety of forms,including, but not limited to a sheet, foam, gel, gauze or a porousmatrix.

FIG. 10 illustrates a structural support 772 that may be disposed withinthe liquid-retention chamber of a wound therapy device. The structuralsupport 772 may be shaped and/or customized to fit within the woundtherapy device. The structural support 772 may include a structuralsupport material 774 that is configured to provide support for the woundtherapy device housing while under a negative pressure. The structuralsupport material 772 may be constructed from rigid or semi-rigidplastics and the like. Disposed between the structural support material774 is an absorbent material 776 for absorbing and retaining woundexudate within the liquid-retention chamber. As described above, theabsorbent material 776 may include sponges; fibers, fabrics or gauzes;super-absorbent material including super-absorbent polymers; absorbentfoams; gelling agents; packing and the like. In some embodiments, theabsorbent material 776 may also serve as structural supports to thehousing while the wound therapy device is under a negative pressure.

FIG. 11 represents another embodiment of a wound therapy device 810,similar to the embodiment depicted and described in conjunction withFIG. 2. The wound therapy device 810 may include a support structure 872within the housing 820. As described in FIG. 10, the support structure872 may include a structural support material 874 and an absorbentmaterial 876 disposed within the liquid-retention chamber 840.

FIG. 12 shows a cross-sectional view of an alternate construction of thepresent wound therapy device. Device 910 includes a vacuum source module911 and a dressing module 913, a coupling 948 maintains the vacuumsource module 911 in communication with the dressing module 913. Thecoupling 948 is configured to transfer negative pressure generated bythe vacuum source module 911 to the dressing module 913. The coupling948 may be an adhesive pad. As discussed above, the coupling may be afeature of the dressing module 913 or the vacuum source module 911, orit may be a separate structure that allows the dressing module 913 to beconnected to the housing module 911. This coupling may be accomplishedby threaded engagement, snap fit, press fit, adhesion, welding, and thelike. The dressing module 913 includes a housing 920 which for examplemay be a flexible barrier or surface wrap that defines an internal space922. This internal space 922 may further include a vacuum chamber 924and a liquid collector 940 separated by a liquid barrier 936. The vacuumchamber 924 in this case is a structural element such as a piece ofplastic with void spaces or channels within for supplying vacuum to theliquid-retention chamber via the liquid barrier. It will be appreciatedby those of skill in the art that the devices described in connectionwith FIGS. 1-11 may also be used in various configurations as thedressing modules 913, 1013, 1113, and 1213 of FIGS. 12-15.

The vacuum source module 911 includes a housing 933 containing a vacuumsource 934, a vacuum switch 944 and a power supply 938. A vacuum sourceoutlet 930 and a vacuum supply inlet 952 for the vacuum switch 944 areconnected to the vacuum chamber 924 through the apertures 925 providedin the flexible barrier housing 920. The vacuum switch 944 can bereplaced by a vacuum sensor/circuit board/relay combination. It iscontemplated that the tubes can be releasably attached to the vacuumchamber to allow the modules 911 and 913 to be detached from oneanother.

FIG. 13 shows a cross-sectional view of a yet another construction ofthe present wound therapy device. Device 1010 includes a vacuum sourcemodule 1011, a dressing module 1013 and a coupling 1048 that maintainsthe vacuum source module 1011 in communication with the dressing module1013. The dressing module 1013 includes a housing 1020 made of aflexible barrier/surface wrap which defines an internal space 1022. Theinternal space in this instance is occupied by the liquid-retentionchamber 1040. Two apertures 1025 are provided on the housing 1020—onefor connecting the vacuum supply and another for connecting a vacuumswitch.

The coupling 1048 is configured to transfer negative pressure generatedby the vacuum source module 1011 to the dressing module 1013. Thecoupling 1048 may include a lip or other structural element of eitherthe vacuum source module 1011 or the dressing module 1013. The coupling1048 may also be a separate member. The coupling allows the vacuumsource module 1011 to be attached to and maintain communication with thedressing module 1013. In one embodiment, the vacuum source module 1011is press fit into the dressing module 1013. In another embodiment, thedressing module 1013 is press fit into the vacuum source module 1011.The modules 1011 and 1013 may cooperate in threaded engagement with eachother. The modules 1011 and 1013 may also be snap fit together or bebonded to one another in addition to other types of engagements. It willbe appreciated by those of skill in the art that the modules 1011 and1013 may be attached to each other in a variety of ways in order topractice the teachings of this invention.

The vacuum source module 1011 includes a housing 1033 containing avacuum source 1034, a vacuum switch 1044 and a power supply 1038. Thehousing 1033 is provided with two apertures 1025—one for the vacuumoutlet 1030 of the vacuum source 1034 and the other for the vacuumsupply inlet 1052 for the vacuum switch 1044. Two liquid barrier films1036 are positioned at apertures 1025. In one embodiment, the vacuumsource module housing 1033 is attached to the dressing module housing1020 using water-barrier adhesive 1048 such that the apertures in thefirst housing and the second housing lineup with the liquid barrier filmin-between. This embodiment is different from earlier embodiments due tothe absence of a vacuum chamber within the first housing, i.e. thevacuum connection 1030 is directly in communication with theliquid-retention chamber 1040 via the liquid barrier 1036. The vacuumswitch can be replaced by a vacuum sensor/circuit board/relaycombination. A fill indicator 1070 along with a sensor 1066 is alsoshown.

FIG. 14 shows a cross-sectional view of a yet another construction ofthe present wound therapy device. Device 1110 is thus shown to include avacuum source module 1111 coupled to a dressing module 1113. Thedressing module 1113 includes a housing 1120 made of a flexiblebarrier/surface wrap which defines an internal space 1122. The internalspace in this instance is occupied by the liquid-retention chamber 1140.The vacuum source module 1111 is attached to the dressing module 1113 bya coupling 1132 or adapter 1132. The vacuum source module 1111 includesa vacuum source 1134, a vacuum sensor 1164 and a power supply 1138. Theadapter 1132 contains a channel that connects a vacuum outlet 1130 fromthe vacuum source 1134 to a liquid barrier film 1136 present in theliquid-retention chamber 1140. The adapter 1132 also carries thecommunication channels between a vacuum sensor 1160 present in theliquid-retention chamber 1140 and a control module 1178 in the vacuumsource module 1111. The control module 1178 may contain circuit boardsand relays known in the art. Leads from a fill indicator sensor 1166,seal sensor (not shown) etc. present in the interior of the housing 1120may also be part of the adapter 1132 or coupling 1032. Further, anycommunications between a pressure relief valve and an over-flow valvepresent on the housing 1120 and the vacuum source 1134 can be channeledthrough such an adapter 1132 or coupling 1132. In some embodiments, theadapter 1132 or coupling 1132 may also function as an on-off switchwhere the vacuum source 1134 as well as other components in the devicewill automatically start functioning when the module 1133 is coupled tothe housing 1120 through the adapter 1132. The vacuum sensor/circuitboard/relay can be replaced by a vacuum switch. A fill indicator 1170along with a sensor 1166 is also shown.

FIG. 15 shows a cross-sectional view of yet another alternateconstruction of the present wound therapy device. Device 1210 is modularsimilar to the embodiments described in connection with FIG. 12-14 andincludes a vacuum source module 1211 and a dressing module 1213. Thedressing module 1213 includes an elongated housing 1220 made of aflexible barrier/surface wrap which defines an internal space 1222. Theinternal space in this instance is occupied by a liquid-retentionchamber 1240 that may contain a liquid collector as discussed above. Thedressing module 1213 includes a wound interface 1241 located at aproximal end of the housing 1220. A negative pressure source 1234 islocated at the other or distal end outside the housing 1220. Theliquid-retention chamber 1240 extends from the wound interface 1241 tothe negative pressure source 1234. An adapter 1232 or coupling 1232 isprovided between a housing 1233 of the vacuum source module 1213 and thehousing 1220 of the dressing module 1213. The vacuum source module 1231contains a vacuum source 1234, a pressure controller 1260 and a powersupply 1238. The pressure controller may be in the form of a pressurerelief valve and may be used to maintain negative pressure within theinternal space 1222 of the housing 1220 (and thus within the retentionchamber 1240 and at the wound surface 1241) at a therapeutic value. Itwill be appreciated by those of skill in the art that the pressurerelief valve can be located anywhere on the device where the vacuum isestablished. The pressure relief valve may also be located on the vacuumsource 1234 itself or on the vacuum connection 1230 (shown) or on thehousing 1220.

The device 1210 may include a moisture disperser 1280 and a vacuumdisperser 1282. The moisture disperser 1280 may facilitate evenabsorption of wound fluids by the liquid-retention chamber 1240 and/orliquid collector. The vacuum disperser 1282 may facilitate evendistribution of vacuum within the liquid-retention chamber 1240 and/orliquid collector. Examples of such vacuum dispersion and moisturedispersers 1282, 1280 include the three-dimensional Knit Spacer Fabricsmanufactured by Gehring Textiles. These spacer fabrics may include twoseparate face fibers that are combined, in a single knitting sequence,with an inner spacer yarn that has a relative perpendicular orientationto the face fibers. Face fibers can be made of, but are not limited to:cotton, nylon, polyester, neoprene, monofilament spandex, PBI, Nomex,Kevlar and fiberglass.

In one embodiment, the vacuum disperser is a surfactant applied to theliquid collector. The vacuum disperser may also be a hydrophobicstructure positioned at the inlet of negative pressure into the housing1220. It will be appreciated by those of skill in the art that thevacuum disperser may preclude the occlusion of the inlet by liquidcollector material.

The retention chamber 1240 and/or the liquid collector 1242 may besingle or multi layered. For example, it may be composed of the liquidcollector 1242 , the vacuum disperser 1282 and the moisture disperser1280. These layers may be present between the liquid collector 1242 andthe liquid barrier 1236 (or vacuum chamber 1224) or between theabsorption layer 1242 and the wound bed.

Without limitation, it is believed that the disclosed devices and theirmethods of use may be useful for the therapy of surface wounds on apatient. These wounds may include, but are not limited to, infectiouswounds, burn wounds, venous and arterial ulcers, diabetic ulcers andwounds, post-surgical wounds, bed sore wounds, and the like.Additionally, such devices are contemplated for use in a variety offields, as would be contemplated by one of ordinary skill in the art.

According to one method of wound treatment or therapy utilizing thedevices described herein, a device having a housing with aliquid-retention chamber is positioned above at least a portion of thewound. Negative pressure may be applied to the wound using the vacuumsource. Wound liquids or exudate may be collected in theliquid-retention chamber. Additionally, the device may be replaced whenit is filled with liquid. In modular embodiments, the liquid-retentionchamber module, wound interface module, or the vacuum source may bereplaced separately or in combination as needed.

A method of assembling a wound therapy device includes the steps ofproviding a vacuum source module comprising a vacuum source capable ofgenerating negative pressure and a pressure controller for controllingthe amount of negative pressure. The method also includes providing adressing module having a housing to cover at least a portion of a woundsite. The dressing module also includes a porous liquid collectorpositioned within the housing and in communication with the wound site.The liquid collector is configured to retain wound exudate whilesimultaneously communicating negative pressure generated by the vacuumsource module to the wound site. The dressing module may also include aliquid barrier positioned between the liquid collector and the vacuumsource module. The dressing module may further include a seal forsealing the dressing module to a surface around the wound site. Themethod includes securing the vacuum source module to the dressingmodule, such that the vacuum source module transfers negative pressureto the dressing module and attaching the device adjacent a wound site.It will be appreciated by those of skill in the art that the methodsteps may be practiced in a number of different orders to practice theteachings of the invention.

In some of the embodiments disclosed, the devices may be adapted to beinexpensive, light-weight, and either partially or entirely disposable.Further, the devices may be adapted to be simple to operate, such thatin some instances, a patient could place the device with some reduceddegree of medical supervision. In addition to the above, the devices maybe constructed so as to be used without attention to their orientation.

It is contemplated that the devices may take a variety of forms,including those that are completely disposable when full, or partiallydisposable such as, for example, either the vacuum source or theliquid-retention chamber. In embodiments such as device 10 of FIGS. 1and 2, it may be that the entire device may be discarded and replacedwhen filled. This may be convenient for smaller wounds, wounds that arealready well along in the healing process, and wounds that are underhome care. Such methods and apparatus prevent and/or reduce contact withpotentially contagious or dangerous bodily liquids.

It should be noted that although the housings disclosed have beenillustrated in particular shapes, such as being generally rounded, thehousings are not necessarily limited to particular shape, and may beconstructed in any advantageous shape. In some embodiments, the devicesmay be sized and shaped such that the vacuum chamber or liquid-retentionchamber is capable of sealing over the patient's wound, at least inpart. The housings and the seals disclosed may be configured to hold avacuum when the device is placed and sealed over at least a portion of awound on a patient's body surface. Such seals may be substantiallyair-tight to prevent the entry of microbes but do not need to beabsolutely impermeable. It is contemplated that vacuum pressure willeither be continuously or periodically applied to maintain a therapeuticnegative pressure therapy range.

When the vacuum is switched on after placing the device on a patient'swound, air is removed around the wound, generating a vacuum within thehousing cavity. At the same time, wound-liquid absorbing material maybegin absorbing the exudate/liquids in the wound. Sustained negativepressure over a wound region may promote tissue migration and woundclosure. In some embodiments, the devices may be shaped like a patch orbandage that may be changed more than once a day. It will be appreciatedby those of skill in the art that the device may continue to absorb andtrap fluid when the device or vacuum is switched off.

Additionally, the device may contain a fill indicator that senses thepresence of free moisture in the liquid-retention chamber that signalsthat the optional porous pad has reached a predetermined absorptivelevel. The fill indicator may in turn be coupled to an over-flow valveto prevent wound liquids from reaching the vacuum pump or it may providea signal used to prompt disabling the pump.

In all of the above embodiments, when the devices are adapted to bedisposable, they may be discarded after use in part or in whole. Indeedmultiple disposable devices can be provided to a patient for a treatmentplan, which may consist of a plurality of individual treatments withdisposable devices over a predetermined period.

Without further elaboration, it is believed that one skilled in the artcan use the preceding description to utilize the present disclosure toits fullest extent. The examples and embodiments disclosed herein are tobe construed as merely illustrative and not a limitation of the scope ofthe present disclosure in any way. It will be apparent to those havingskill in the art that changes may be made to the details of theabove-described embodiments without departing from the underlyingprinciples of the disclosure provided herein. In other words, variousmodifications and improvements of the embodiments specifically disclosedin the description above are within the scope of the appended claims.Note that elements recited in means-plus-function format are intended tobe construed in accordance with 35 U.S.C. §112 ¶6. The scope of theinvention is therefore defined by the following claims.

1. A wound therapy device, comprising: a housing configured to cover atleast a portion of a wound; a vacuum source in fluid communication withthe housing; a liquid collector positioned inside of the housing and inoperable communication with the wound, wherein said liquid collector isconfigured to retain wound exudate while simultaneously communicatingnegative pressure generated by the vacuum source to the wound.